Object-oriented models are a popular basis for supporting uniform sharing of data and services in operating systems, distributed programming systems, and database systems. We term systems that use objects for these purposes object sharing systems. Operating systems in common use have nonuniform addressing models, making the uniform object naming required by object sharing systems expensive and difficult to implement. We argue that emerging 64-bit architectures make it practical to support

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... m naming at the virtual addressing level, eliminating a key implementation problem for object sharing systems. We describe facilities for object-based sharing of persistent data and services in Opal, an operating system we are developing for paged 64-bit architectures. The distinctive feature of Opal is that object sharing is supported in a runtime library, a,bove a single virtual address space that maps all primary and secondary storage in a local area network.